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Manufacture and research of artificial aggregates made from organic wastes.
No full textThe Master's thesis analyses the production and use of artificial fillers made from organic waste in mortars. The aim of the thesis is to develop an environmentally friendly artificial aggregate made from wood sawdust and shale ash for use in cement mortars. Furthermore, it is investigated how different types of chemical additives influence the interaction between the hydration of wood sawdust and cement composite. The literature analysis part reviews the chemical composition of wood and which compounds in wood weaken the hydration of cement. The effect of wood on the physical and mechanical properties of the cement-wood composite is also reviewed. The theoretical part analyses the possible ways and chemicals to counteract the negative effects of sawdust on the interaction with cement. The presently known cement hydration accelerators and their principles of operation are reviewed. In the experimental part, artificial aggregates of different compositions were produced and analysed, and one composition was selected for further investigations in mortars. In further studies, mortars were created by replacing the volumetric sand with the developed artificial aggregate. The effect of the aggregates on the physical and mechanical properties of the mortars, as well as on the resistance to surface freezing and thawing, was determined by laboratory tests. Calculations of the CO2 footprint for the production of different mortar compositions were carried out
Relationship between school principal’s leadership and teachers’ engagement in digital transformation activities.
No full textThis master thesis analyses the relationship between school leaders' leadership and teachers' engagement in digital transformation activities. Digital transformation, as one of the most important innovations in the education sector, requires strategic leadership from principals and the active involvement of educators. Leaders' roles include creating a vision, motivating educators, promoting their professional development and ensuring technology integration. Meanwhile, educators' involvement helps to create innovative learning environments and to implement digital change effectively. The paper focuses on the links between school leaders' leadership and educators' engagement in digital transformation activities. The aim of the paper is to reveal how school leaders' leadership influences educators' engagement in digital transformation processes and their professional development. The study is based on a literature review, a quantitative study (questionnaire survey) and a correlation analysis in order to reveal the links between school leaders' leadership approaches and teachers' engagement in digital transformation activities. The correlation analysis allowed us to assess how leaders' strategic actions - visioning, motivating teachers, managing the technological infrastructure - are related to teachers' digital competences, motivation for digital change, emotional well-being and collegial collaboration. The results of the study showed that the ability of leaders to develop a clear vision and goals for digital transformation is closely linked to the development of teachers' technological competences. Leaders who actively invest in building technological infrastructure, support teachers' professional development and focus on digital literacy are found to contribute to significant changes in school performance. The strongest links were found between leaders' actions and teachers' digital literacy and security knowledge. This shows that leaders, by demonstrating a strong commitment to digital transformation, enable teachers to use digital tools safely and effectively in their teaching. The weakest links were identified in the context of collegial collaboration in digital education. This reveals that leaders' influence in this area is less direct and more often focused on developing individual teachers' skills rather than on strengthening a culture of peer collaboration. These results suggest that school leaders should focus more on teamwork, encouraging teachers to share experiences and developing a collaborative and innovative culture. In summary, the study reveals that school leaders' leadership plays a key role in the context of teachers' engagement in digital transformation activities. Transformational and shared leadership models are particularly significant as they promote educators' participation in decision-making, motivation and professional growth. However, to ensure the full engagement of teachers, leaders should focus more on building a culture of collaboration, fostering interaction and creating an environment where teachers feel not only supported but also actively involved in strategic decisions. The recommendations made in this paper highlight the role of school leaders in the digital transformation process. It recommends that leaders strengthen the involvement of teachers in strategic change plans, promote professional development through training in the use of technology, and develop initiatives that support the promotion of collegial collaboration. Education policy makers are encouraged to ensure continued support for technology funding, support professional development programmes and promote peer-to-peer collaboration mechanisms at school level to increase the effectiveness and sustainability of digital transformation
Research and application of lightweight concrete produced using silica aerogel.
No full textThe aim of this master's thesis is to study lightweight concrete containing silica aerogel. The work is carried out in three stages: review of scientific literature, experimental part and case analysis. The literature review examines the use of silicon aerogel in concrete, as well as the materials that best interact with this product in concrete production, the properties of such cementitious composites and their possible uses. Although numerous studies have concluded that aerogel significantly improves the thermal properties of concrete, further experiments are needed to determine the effectiveness of this application. In this experiment, samples were prepared to test the mechanical properties of concrete such as density, compressive strength, and flexural strength. Based on the composition obtained with the best results, samples were also prepared for thermal conductivity testing, and the coefficient of thermal conductivity was determined. To evaluate the efficiency of using such concrete in construction and considering the determined properties of the cementitious composite, an analysis was conducted. This analysis demonstrated how the investigated concrete impacts various structural nodes in terms of heat transfer and how it increases construction costs
Relationship between sustainable leadership and employees' socially responsible behaviour.
No full textLeadership is recognised as a long-term approach and activity aimed at managing, supporting, and motivating employees in a socially responsible and cost-effective manner. Employees play a crucial role in achieving sustainability objectives through their daily activities, responsible behaviour, and commitment to the organisation's values and strategies. Based on this foundation, sustainable leadership emerges as a pivotal element in building more sustainable business models. However, while these concepts are theoretically linked, the question arises: what are the links between sustainable leadership and employees' socially responsible behaviour within organisations? The subject of the paper is sustainable leadership in the development of socially responsible behaviour. The aim of the paper is to show the links between sustainable leadership and employees' socially responsible behaviour. The objectives of the thesis are: to analyse the concept of sustainable leadership, highlighting its features; to analyse the concept of socially responsible behaviour of employees and the features of its expression at work; to identify the links between sustainable leadership and socially responsible behaviour of employees. The literature highlights that socially responsible behaviour involves employees' conscious engagement in voluntary initiatives, community projects, and sustainability strategies both within and beyond the organisation. Sustainable leadership, on the other hand, is defined as an integrated management approach, implemented through collaborative efforts to shape organisational culture, enhance performance, and reconfigure work systems to align with emerging sustainability goals. The findings of this study indicate that sustainable leadership is significantly correlated with employees' engagement in environmentally friendly tasks and initiatives. However, the research also reveals a weaker correlation between sustainable leadership and employees' active participation in socially responsible activities initiated by the organisation. This suggests that while sustainable leadership effectively encourages responsible behaviour, its impact is limited, particularly in activities outside the organisation. These findings point to a gap in perceived support from managers and a lack of sufficient incentives and opportunities for employees' ideas to be valued and implemented. To address these challenges and strengthen the connection between sustainable leadership and socially responsible behaviour, several recommendations are proposed. Organisations should actively involve employees in the development of sustainability plans. Regular meetings and discussions should be organised to foster the sharing of ideas, exchange of experiences, and provision of feedback. Empowerment strategies are crucial to enable employees to independently pursue environmentally friendly initiatives, complemented by robust support systems that motivate participation in social and environmental activities. Leadership training, particularly in emotional intelligence, is also vital to enhance leaders' ability to understand and positively influence employee engagement. Finally, managers should be encouraged to engage directly with communities to better understand societal needs and foster stronger connections between the organisation and its external environment
Evaluation of the factors of Lithuania’s export development.
No full textGlobalization, integration, and rapid economic development influence the world's international markets and the economic decisions made. The importance of international trade was recognized and emphasized as early as the Mercantilist era. Since then, international trade and its tools and forms have significantly evolved. Currently, principles of free trade prevail. A country's specialization, economic factors, development of infrastructure, political environment, and other factors have influenced the formation and expansion of international trade. Therefore, exports are affected by economic-political environment factors, social-legal environment factors, technological environment factors, and ecological environment factors. Countries do not compete with each other; rather, companies and organizations compete for market share and greater benefits. However, the state plays a significant role in developing and supporting these environmental factors. Each country is interested in promoting exports, as exports are indeed the main driving force of economic and technological advancement. When describing a country's level of competitiveness, the volume and structure of its exports are observed. Exporting high-tech products or providing knowledge-intensive services creates greater benefits for the overall gross domestic product
3D printable piezoelectric composites manufactured via scalable and sustainable solvent-free multi-extrusion process /
No full textModification of thermally activated delayed fluorescence emitters comprising acridan-pyrimidine and spiro-acridan-pyrimidine moieties for efficient triplet harvesting /
No full textIn this study, we investigate the effect of substitution and conformational impact on the photophysical properties of novel 5-methylpyrimidine derivatives containing electron-donating groups with distinct rigidity. Research has revealed that all of the compounds showed pronounced thermally activated delayed fluorescence (TADF) features. The addition of the spiro-acridan moiety eliminated dual emission, simplifying the photophysical behavior of the compounds. Compounds containing spiro-acridan units exhibited a larger singlet−triplet energy gap, resulting in a reduced reverse intersystem crossing rate and an extended TADF lifetime in both toluene solutions and PMMA films. Additionally, the delayed fluorescence intensity was higher in these compounds, which was attributed to a slower nonradiative triplet quenching rate. Embedding TADF compounds into a rigid PMMA matrix significantly increases the quantum yield of delayed emission by minimizing nonradiative deactivation caused by intramolecular twisting. The considerable conformational disorder in the polymer-doped films leads to multiexponential fluorescence decay and noticeable shifts in both prompt and delayed fluorescence in time-resolved spectra. The attachment of electron-donating moieties at the fourth position in 5-methylpyrimidine reduces conformational disorder due to the restriction of the rotations caused by methyl attachment
On the security of the STR key exchange protocol /
No full textIn this paper, we consider the security of the Sakalauskas-Tvarijonas-Raulynaitis (STR) key exchange protocol. We perform an analysis by exploring various cases of the canonical form of the publicly known matrix using elements of linear algebra and number theory. Additionally, we consider the multiplicative order of matrices and show how these two factors affect the security of the considered protocol. We show that regardless of the choice of publicly known matrix, the considered protocol is secure under the discrete logarithm assumption. In other words, if at least one of the secret exponents is found, then the STR protocol can be broken in polynomial time
Environmental assessment of mycelium based straw insulation composite: a sustainability analysis at building material level /
No full textThe construction industry is increasingly adopting sustainable materials to mitigate environmental impacts. This study evaluates the environmental performance of Mycelium-Based Straw Insulation Composite (MBSIC), an innovative material combining mycelium and agricultural waste to create a biodegradable, lightweight, and thermally efficient insulation alternative. A Life Cycle Assessment (LCA), following ISO 14040 standards, examines the environmental impacts of MBSIC from raw material extraction to transportation, identifying opportunities for sustainability optimization. Additionally, a Multi-Criteria Analysis (MCA) compares MBSIC with conventional insulation materials based on cost, durability, and aesthetics. The methodology involves a cradleto-gate LCA approach, assessing greenhouse gas emissions, resource consumption, and environmental impact categories such as global warming potential, acidification, and human toxicity. Two production scenarios—standard room conditions and climate chamber cultivation—are analyzed to determine their respective environmental implications. MCA integrates expert evaluations using Simple Additive Weighting (SAW) and Multiplicative Exponential Weighting (MEW) methods to assess MBSIC’s comparative performance. Results indicate that MBSIC produced under standard room conditions significantly reduces greenhouse gas emissions and resource consumption compared to climate chamber cultivation. MCA findings demonstrate that MBSIC outperforms traditional insulation materials, such as rock and glass mineral wool, in key sustainability metrics. The study underscores MBSIC’s potential for integration into sustainable construction practices, offering valuable insights for policymakers, industry stakeholders, and researchers
Exploring the Emotional geography of Kaunas city center: a mixed-method approach to understanding place identity /
No full textTraditional urban analysis and planning often neglect intangible emotional responses, leaving a gap in comprehending and addressing appropriately how urban spaces are experienced by individuals and communities. However, in contemporary urban research, emotional dimensions have increasingly been recognized as integral to understanding place and its identity, although the methods for systematically mapping these emotions and addressing both their qualitative and quantitative aspects remain under development. In order to address this research gap, this study presents an analysis of the emotional geography of Kaunas city (Lithuania) center using a mixed-method approach combining qualitative and quantitative methods to examine public narratives collected from social media posts and comments and open-ended responses from a sociological survey of local residents. A qualitative approach, grounded in the classification of emotions by Plutchik, was applied in order to categorize emotional expressions. Simultaneously, a quantitative sentiment analysis using the NLTK VADER tool was performed in order to assess the polarity of emotions and classify them into Positive, Negative, or Neutral within the collected narratives. The social media posts and comments were then georeferenced and mapped using Geographic Information Systems (GISs), while survey data were manually linked to specific locations. This allowed for the creation of emotion maps that highlight emotional hotspots and spatial sentiment trends within Kaunas city center. The results reveal how varying emotional responses are geographically connected to different areas, providing insights into both emotional responses to qualities of physical space and activities directly and indirectly linked to this space. Furthermore, the study demonstrates the potential of emotional mapping as a tool for urban planning, place-making, and sustainable development